1. Field of the Invention
The present invention relates to an airbag apparatus for a side window of a vehicle that so inflates and deploys an airbag as to shut the side window in order to protect a head of an occupant in the event of a side impact, and particularly relates to an airbag apparatus in which an airbag prevents an occupant from ejecting out of the vehicle via the window during a rollover event.
2. Description of Related Art
A known airbag apparatus for a vehicle side window is provided with an airbag mounted on the upper periphery of a window located between front and rear pillars. The airbag includes a shutter section that develops downward from the upper periphery of the window and covers the window on an inboard side thereof.
JP 2001-328503 is illustrative of one such airbag apparatus for a side window. The shutter section of the airbag of the airbag apparatus extends up to below the beltline of a door so as to be supported at the lower end by an interior surface of the vehicle body structure, and thus an ejection of an occupant is securely prevented.
JP2010-36805 discloses an airbag apparatus for a side window wherein a shutter section of its airbag includes at the lower end an inflatable portion that is formed in a doubled fashion and deployable below the beltline of a door so as to hold an occupant from moving to an exterior of a vehicle.
Further, an airbag apparatus for a side window illustrated in JP2003-237521 includes an airbag provided at a first end in a front and rear direction with an oblique inflatable portion that extends obliquely from the bottom to top.
In the airbag apparatuses of JP2001-328503 and JP2010-36805, however, the shutter section has an inflatable portion at the region to be supported by the interior surface of the vehicle body structure below the beltline in addition to the inflatable portion for covering the window. Such a configuration will increase the volume of the airbag and require a bulky and heavy inflator with a large output. Especially if such an airbag is made for a vehicle with three rows of seats for covering all the windows between a front pillar and a rear pillar, an even larger inflator will be required.
It seems that the airbag of JP2003-237521 gives a solution to the above problem because the oblique inflatable portion is partially provided, not over an entire window, and therefore reduces the volume of the airbag. However, the oblique inflatable portion merely acts as a tension belt for generating a tension in a front and rear direction on the lower edge of the airbag, and the oblique and partial arrangement of the oblique inflatable portion provides a void region in front of the oblique inflatable portion. Therefore this airbag is deficient in the event that an occupant's head enters the void region at a side impact.